Osteology
|
| Bone |
Structure |
Description |
Notes |
| pubis (N468, TG3-05, TG3-05) |
|
an angulated bone that forms the anterior part of the pelvis |
one of three bones that form the os coxae: ilium, ischium, pubis; its body forms 1/5 of the acetabulum; its symphyseal surface unites with the pubis of the opposite side to form the pubic symphysis; the superior and inferior pubic rami participate in the formation of the obturator foramen |
|
body |
superolateral portion of the pubis |
the body of the pubis forms about 1/5 of the acetabulum |
|
pecten |
ridge on superior surface of the superior pubic ramus |
attachment point of the pectineal ligament; also called the pectineal line |
| ilium (N468, TG3-05, TG3-05) |
|
fan-shaped bone that forms the lateral prominence of the pelvis |
one of three bones that form the os coxae: ilium, ischium, pubis |
|
arcuate line |
ridge running from anteroinferior to posterosuperior on the inner surface of the ilium |
inferior boundary of the iliac fossa; marks the plane of transition from abdominal cavity to pelvic cavity (Latin, arucate = bowed) |
| sacrum (TG6-04, TG6-04) |
|
a triangular bone that is the posterior skeletal element forming the pelvis |
it is formed by 5 fused vertebrae; the sacrum and two os coxae bones form the pelvis (Latin, sacrum = sacred bone) |
|
promontory |
a projection of the superior part of the sacrum in an anterior direction |
the body of the fifth lumbar vertebra sits on the sacral promontory and articulates with it through a symphysis |
| iliopectineal line (N468, TG3-05, TG3-05) |
|
the union of pectineal and arcuate lines |
together with the ala of the sacrum and the sacral promontory, this line (also known as the linea terminalis) marks the pelvic brim or the boundary between false pelvis above and true pelvis below |
Nerves
|
| Nerve |
Source |
Branches |
Motor |
Sensory |
Notes |
| vagus n. (TG5-40, TG7-13, TG7-15, TG7-25) |
medulla: dorsal motor nucleus (GVE preganglionic parasympathetic); inferior ganglion (GVA); nucleus ambiguus (SVE); superior ganglion (GSA); inferior ganglion(SVA) |
auricular br., pharyngeal br., superior laryngeal, superior and inferior cervical cardiac brs., recurrent laryngeal n., thoracic cardiac brs., brs. to the pulmonary plexus, brs. to the esophageal plexus, anterior and posterior vagal trunks |
SVE: intrinsic muscles of the larynx, pharynx (except stylopharyngeus), and palate (except tensor veli palatini); GVE: smooth muscle of the respiratory tree & gut (proximal to the left colic flexure), heart; secretomotor: mucous glands of the larynx, respiratory tree, pharynx and gut; secretomotor to digestive glands |
GSA: skin of the external auditory meatus; GVA: viscera of head, neck, thorax & abdomen proximal to the left colic flexure; SVA: taste from the epiglottis |
also known as: CN X, 10th cranial nerve; the vagus n. passes through the jugular foramen to exit the posterior cranial fossa; (Latin, vagus = wanderer, so called due to its wide distribution to the body cavities) |
| mesenteric plexus, inferior (TG5-39) |
intermesenteric plexus |
multiple unnamed nn. course along the branches of the inferior mesenteric a. |
sympathetic: smooth muscle of the vessels supplying the descending colon, sigmoid colon and rectum |
pain from the descending colon, sigmoid colon and rectum |
inferior mesenteric plexus contains no vagal parasympathetic fibers; pelvic splanchnic n. axons join the most distal nn. of the plexus near gut wall (Latin, plexus = a braid) |
| mesenteric plexus, superior (TG5-39) |
celiac plexus, superior mesenteric ganglion |
multiple unnamed nn. course along the branches of the superior mesenteric a. |
sympathetic: smooth muscle of vessels supplying the lower pancreas, lower duodenum, jejunum, ileum, cecum, ascending colon and most of the transverse colon; parasympathetic (vagus): smooth muscle in the gut wall of same distribution area |
pain & GVA of the parts of the gut named at left |
superior mesenteric plexus contains a mixture of vagal (preganglionic parasympathetic) axons and postganglionic sympathetic axons (Greek, mesos = middle + enteron = intestine; Latin, plexus = a braid) |
| pelvic splanchnic nn. (TG5-40, TG5-41) |
ventral primary rami of spinal nerves S2-S4 (cell bodies are located in the lateral horn gray of the sacral spinal cord) |
unnamed branches contribute to the pelvic plexus (inferior hypogastric) plexus |
smooth muscle and glands of the gut distal to the left colic flexure; smooth muscle and glands of all pelvic viscera |
none |
parasympathetic nerves; these contain preganglionic parasympathetic axons (Greek, splanchna = viscera) |
Arteries
|
| Artery |
Source |
Branches |
Supply to |
Notes |
| appendicular (N295, TG5-13, N296, TG5-15) |
posterior cecal, anterior cecal or ileocolic |
no named branches |
vermiform appendix |
despite its variable origin, appendicular artery is nearly constant in its course posterior to the terminal part of the ileum |
| cecal, anterior |
ileocolic a. |
may give off the appendicular a. |
anterior surface of the cecum |
anterior cecal a. supplies the ileocecal junction (Latin, cecum = blind) |
| cecal, posterior |
ileocolic a. |
may give off the appendicular a. |
posterior surface of the cecum |
posterior cecal a. supplies the ileocecal junction (Latin, cecum = blind) |
| colic, left(N296, TG5-14) |
inferior mesenteric a. |
ascending br., descending br. |
descending colon |
left colic a. anastomoses with the middle colic a and the sigmoid a.to form part of the marginal a. |
| colic, middle (N296, TG5-13) |
superior mesenteric |
right br., left br. |
transverse colon |
middle colic a. anastomoses with the right colic a. and the left colic a. to form part of the marginal a. |
| colic, right (N295, TG5-13) |
superior mesenteric (or br. of) |
ascending br., descending br. |
ascending colon |
right colic a. anastomoses with the ileocolic a. and the middle colic a. to form part of the marginal a. |
| ileocolic (N295, TG5-13, N296, TG5-14) |
superior mesenteric a. |
colic br., anterior cecal br., posterior cecal br., appendicular a., ileal br. |
cecum, appendix, terminal portion of the ileum |
colic br. of the ileocolic a. participates in the formation of the marginal a. |
| intestinal (N295, TG5-13) |
superior mesenteric a. |
arterial arches |
jejunum, ileum |
intestinal aa. are 12-15 in number and are found in the mesentery |
| marginal (N296, TG5-14A, TG5-14B) |
formed by anastomoses of branches of the ileocolic a., right colic a., middle colic a., left colic a., sigmoid a. |
colic brs. |
colon |
an important anastomosis for the large intestine |
| mesenteric, inferior (N256, TG5-34, N295, TG5-13, N296, TG5-14, N300, N301, TG5-14, N302, TG5-28) |
abdominal aorta at the level of the L3 vertebral body |
left colic a., sigmoid aa.(2-3), superior rectal a. |
splenic flexure, descending colon, sigmoid colon, superior part of rectum |
branches of the inferior mesenteric a anastomose in the marginal artery (Greek, mesos = middle + enteron = intestine) |
| mesenteric, superior (N256, TG5-34, N295, TG5-13, N296, TG5-14, N300, N301, TG5-14, N302, TG5-28) |
abdominal aorta at the level of the lower 1/3 of the L1 vertebral body |
inferior pancreaticoduodenal a., middle colic a., jejunal a., ileal a., right colic a., ileocolic a. |
inferior part of the head of the pancreas, distal duodenum, jejunum, ileum, cecum, appendix, ascending colon, transverse colon |
superior mesenteric a. supplies the midgut derivatives; brs. of the superior mesenteric a. participate in formation of the marginal artery (Greek, mesos = middle + enteron = intestine) |
| rectal, superior (N296, TG5-14) |
inferior mesenteric a. |
two unnamed branches |
superior part of the rectum |
superior rectal a. is the continuation of the inferior mesenteric a. after the sigmoid brs. are given off; it anastomoses with the middle rectal a. and the inferior rectal a. |
| sigmoid (N296, TG5-14) |
inferior mesenteric a. |
ascending br., descending br. |
sigmoid colon |
sigmoid aa. are 2-3 in number; they anastomose with the left colic a. to help form the marginal a. (Greek, sigmoid = resembles the greek letter sigma) |
Viscera
|
| Organ/Part of Organ |
Location/Description |
Notes |
| appendix, vermiform (N273, TG5-15A, N274, TG5-15B, TG5-15C,
N276) |
terminal portion of the cecum which has a small dead-end lumen |
vermiform appendix is attached to the posteroinferior surface of the cecum;
it is usually located behind the cecum in the right iliac fossa; pain from
the appendix projects to McBurney's point on anterior abdominal wall (1/3rd
distance along and imaginary line from the anterior superior iliac spine
to the umbilicus); it has a complete peritoneal covering and a small mesentery
(mesoappendix) (Latin, vermiform =
worm-shaped) |
| appendix epiploica(N273, TG5-15A, N274, TG5-15B, TG5-15C, N276) |
fat-filled pendants of peritoneum projecting from the visceral peritoneum on the surface of the large intestine |
there are many appendices epiploices on the large intestine (except the rectum) and none on the small intestine; also known as: omental appendage |
| ascending colon (N276, TG5-12B) |
part of the large intestine that is continuous with the cecum proximally and the transverse colon at the right colic (hepatic) flexure |
ascending colon is retroperitoneal |
| cecum (TG5-15A, TG5-15B) |
first part of the large intestine which is located in the right lower quadrant |
cecum is continuous with the ileum (small intestine) at the ileocecal valve; it is continuous with the ascending colon distally; it is intraperitoneal but lacks a mesentery; the vermiform appendix is attached to its posteroinferior surface (Latin, cecum = blind) |
| descending colon (N276, TG5-12B) |
part of the large intestine that is continuous with the transverse colon at the left colic (splenic) flexure and the sigmoid colon at the pelvic brim |
descending colon is retroperitoneal |
| duodenojejunal junction (N262, TG5-14, TG5-26) |
part of the small intestine where the duodenum is continuous with the jejunum |
duodenojejunal junction is located in the left upper quadrant; it is suspended by the suspensory muscle (ligament) of the duodenum; the inferior mesenteric v. passes to left side of the duodenojejunal junction |
| haustra (N276, TG5-12B) |
multiple pouches in the wall of the large intestine |
haustra form where the longitudinal muscle layer of the wall of the large intestine is deficient; also known as: sacculations (Latin, haustra = a machine for drawing up water) |
| hepatic flexure (N276, TG5-12B) |
junction of the ascending colon and the transverse colon |
hepatic flexure lies anterior to the lower part of the right kidney and inferior to the right lobe of the liver; also known as: right colic flexure |
| ileocecal junction(N273, TG5-15A, TG5-15B) |
point at which the ileum joins the cecum |
ileocecal valve moderates the flow of intestinal contents from the ileum into the cecum |
| ileocecal valve (N274, TG5-15B,
N276) |
a valve that marks the ileocecal junction |
ileocecal valve is incompetent, not a sphincter; it has superior and inferior lips |
| ileum (N261, TG5-12B, N272, TG5-16) |
most distal part of the small intestine |
ileum is continuous with the jejunum proximally and terminates at ileocecal junction distally; it is approximately 12 feet in length; it has a thinner wall than the jejunum, lower plicae circulares than the jejunum, more fat in its mesentery than does the jejunum, more complex arterial arcades than the jejunum, shorter arteriae recta than the jejunum |
| intestine, large (N276, TG5-12B) |
part of the intestinal tract distal to the small intestine |
large intestine is approximately 5 feet long; parts of the large intestine are: cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum; also known as: colon or large bowel |
| intestine, small (N261, TG5-16, TG5-12B) |
part of the intestinal tract between the stomach proximally and the large intestine distally |
small intestine is approximately 21 feet long; parts of the small intestine are: duodenum (1 foot long, mostly retroperitoneal); jejunum (8 feet long); ileum (12 feet long) |
| jejunum (N261, TG5-12, N272, TG5-16) |
part of the small intestine that is continuous with the duodenum proximally (at the duodenojejunal junction) and the ileum distally (no obvious landmark for its termination) |
jejunum is approximately 8 feet in length; wall of the jejunum is thicker than the wall of the ileum; plicae circulares (circular folds) are more pronounced in the jejunum than in the ileum; mesentery of the jejunum has less fat than that of the ileum; arterial arcades of the jejunum are simpler than those of the ileum; arteriae recta are longer in the jejunum than they are in the ileum |
| left colic flexure (N276, TG5-12B) |
junction of the transverse colon and descending colon |
left colic flexure lies anterior to the left kidney and inferior to the spleen; also known as: splenic flexure |
| omental appendage (N263, N276, TG5-12B) |
fat-filled pendants of peritoneum projecting from the visceral peritoneum on the surface of the large intestine |
there are many omental appendages on the large intestine (except the rectum) and none on the small intestine; also known as: appendix epiploica (Latin, omentum = the membrane which encloses the bowels) |
| right colic flexure (N276, TG5-12B) |
junction of the ascending colon and the transverse colon |
right colic flexure lies anterior to the lower part of the right kidney and inferior to the right lobe of the liver; also known as: hepatic flexure |
| sigmoid colon (N276, TG5-12B) |
part of the distal large intestine located within the lower left quadrant |
sigmoid colon is continuous proximally with the descending colon at the left pelvic brim; it is continuous distally with the rectum at the level of the 3rd sacral vertebra; it is suspended from posterior abdominal wall by the sigmoid mesocolon (Greek, sigmoid = resembles the greek letter sigma) |
| stomach (N261, TG5-12, TG5-18) |
dilated portion of the digestive system located primarily in the upper left quadrant |
stomach rotates during embryonic development so that the lesser curvature (originally the anterior surface) faces superiorly and to the right, the greater curvature (originally the posterior surface) faces inferiorly and to the left |
| teniae coli (N276, TG5-12B) |
band of longitudinal smooth muscle on the surface of the large intestine |
there are three teniae coli, named according to their position on the transverse colon: tenia omentalis (located at the line of attachment of the omental apron), tenia mesocolica (located at the line of attachment of the transverse mesocolon), tenia libera ("free" tenia - it has no mesenteric attachment obscuring it) (Latin, tenia = band or tape) |
| transverse colon (N276, TG5-12B) |
part of the large intestine located between the left and right colic flexures |
transverse colon is continuous proximally with the ascending colon at the right colic (hepatic) flexure; it is continuous distally with the descending colon at the left colic (splenic) flexure; it is suspended from the posterior abdominal wall by the transverse mesocolon |
Peritoneal Specializations and Associated Structures
|
| Specialization |
Location/Description |
Notes |
| gastrocolic ligament (N261, TG5-18) |
peritoneum connecting the greater curvature of the stomach with the transverse colon |
part of the greater omentum; derived from the dorsal mesogastrium in the embryo |
| gastrolienal ligament |
peritoneum connecting the greater curvature of stomach with the hilum of the spleen |
part of the greater omentum; derived from the dorsal mesogastrium in the embryo; also known as: gastrosplenic ligament |
| gastrophrenic ligament |
peritoneum connecting the fundus of the stomach to the left side of the diaphragm above the spleen |
part of the greater omentum; derived from the dorsal mesogastrium in the embryo |
| gastrosplenic ligament (N261, TG5-18) |
peritoneum connecting the greater curvature of stomach with the hilum of the spleen |
part of the greater omentum; derived from the dorsal mesogastrium in the embryo; also known as: gastrolienal ligament |
| greater omentum (adult dorsal mesogastrium) (TG5-12), TG5-18) |
apron-like specialization of peritoneum attaching along the greater curvature of the stomach |
subdivisions: gastrophrenic ligament, gastrosplenic ligament, gastrocolic ligament, omental apron (Latin, omentum = the membrane which encloses the bowels) |
| greater peritoneal sac |
the portion of the peritoneal cavity that is not located posterior to the stomach |
the lesser peritoneal sac is the only part of the peritoneal cavity that is not part of the greater peritoneal sac |
| hepatoduodenal ligament (TG5-18) |
part of the lesser omentum connecting the liver to the 1st part of duodenum |
hepatoduodenal ligament contains the common bile duct, proper hepatic a. and portal v.; it forms the anterior wall of the omental (epiploic) foramen |
| hepatogastric ligament (TG5-18) |
part of the lesser omentum connecting the liver to the lesser curvature of the stomach |
hepatogastric ligament forms the anterior wall of the lesser peritoneal sac |
| omental apron (N261, TG5-12) |
part of the greater omentum that hangs inferiorly from the transverse colon |
omental apron is derived from the dorsal mesogastrium during development (Latin, omentum = the membrane which encloses the bowels) |
| omental bursa (TG5-18) |
part of the peritoneal cavity located posterior to the stomach and lesser omentum |
omental bursa is continuous with the greater peritoneal sac at the omental (epiploic) foramen; also known as: lesser peritoneal sac |
| omental foramen (TG5-18) |
passageway between the greater peritoneal sac and the lesser peritoneal sac |
located posterior to the hepatoduodenal ligament; also known as: epiploic foramen |
| lesser omentum (adult ventral mesogastrium) (TG5-18) |
peritoneum stretching between the lesser curvature of the stomach and the visceral surface of the liver |
subdivisions of the lesser omentum are the heptogastric and hepatoduodenal ligaments; lesser peritoneal sac (omental bursa) lies posterior to the lesser omentum and stomach (Latin, omentum = the membrane which encloses the bowels) |
| lesser peritoneal sac (TG5-18) |
part of the peritoneal cavity located posterior to the stomach and lesser omentum |
lesser peritoneal sac is continuous with the greater peritoneal sac at the omental (epiploic) foramen; also known as: omental bursa |
| lienorenal ligament |
peritoneum that attaches the spleen to the posterior abdominal wall over the left kidney |
lienorenal ligament develops from the dorsal mesogastrium of the embryo; also known as: splenorenal ligament |
| mesentery (N295, TG5-13,N335) |
peritoneum connecting jejunum & ileum to posterior abdominal wall |
also known as: mesentery of small intestine (Greek, meso = in the middle of + enteron = intestine) |
| mesoappendix (N273, TG5-15) |
peritoneum connecting the vermiform appendix to the mesentery of the small intestine |
the appendix has its own mesentery which contains its blood supply - a clinically relevant detail during appendectomy |
| anterior cecal fold (N273, TG5-15) |
peritoneal fold passing from the mesentery to the anterior surface of the cecum |
contains the anterior cecal artery |
| ileocecal fold (N273, TG5-15) |
peritoneal fold passing from the ileum to the cecum, inferior to the ileocecal junction |
avascular; contains no major artery |
| peritoneum |
serous membrane lining the peritoneal cavity |
visceral peritoneum lies on the surfaces of the abdominal and pelvic organs; parietal peritoneum lines the inner surfaces of the walls of the abdominopelvic cavity |
| peritoneum, parietal (N335,N336, TG5-42, N337, TG5-43) |
serous membrane lining the inner surfaces of the walls of the abdominopelvic cavity |
peritoneum, pleura and pericardium are all serous membranes that formed
from the same layer of tissue (splanchnic mesoderm) in the embryo (Greek,
peritonaion = stretch around) |
| peritoneum, visceral (N335, N336, TG5-42, N337, TG5-43) |
serous membrane lying on the surfaces of the abdominal and pelvic organs |
visceral peritoneum is formed from the splanchnic mesoderm in the embryo
(Greek, peritonaion = stretch around) |
| sigmoid mesocolon (N276, N296, TG5-14) |
peritoneum connecting the sigmoid colon to posterior abdominal wall |
branches of the inferior mesenteric a. approach the sigmoid colon within the sigmoid mesocolon; ascending preganglionic parasympathetic axons course through the sigmoid mesocolon in their route from the pelvis (S2,3,4) to the descending colon (Greek, sigmoid = resembles the greek letter sigma) |
| splenorenal ligament (N261, TG5-20) |
peritoneum that attaches the spleen to the posterior abdominal wall over the left kidney |
splenorenal ligament develops from the dorsal mesogastrium of the embryo; also known as: lienorenal ligament |
| transverse mesocolon (N276, N296, TG5-14) |
peritoneum connecting the transverse colon to the posterior abdominal wall |
transverse mesocolon represents the fusion of the transverse mesocolon with one layer of the greater omentum in the embryo; it forms the floor of the lesser peritoneal sac |
| falciform ligament (N261, TG5-12) |
sickle-shaped fold of peritoneum connecting liver to umbilicus |
contains round ligament of liver (ligament teres hepatis) (Latin and English combo, falciform = shaped like a scythe or sickle) |
Clinical Terms
|
| Term |
Definition |
| Meckel's diverticulum |
an out-pouching of the small bowel (ileum). Present in about 2% of people and usually occurs
about 2 feet before the junction with the cecum. Can be lined by stomach-type mucosa and
ulcerate, perforate, or cause small bowel obstruction. This is caused by failure of the vitelline
duct to obliterate during embryologic development. They are true diverticula, meaning that
they affect all three muscle layers of the intestinal wall. |
| omphalocele |
herniation of abdominal viscera through umbilical and supraumbilical abdominal wall into a sac covered by peritoneum and amniotic membrane. This sac is thin and can easily rupture. Seen in neonatology. (Greek, omphal- = navel + -cele = hernia) |
| gastroschisis |
herniation of abdominal viscera through the abdominal wall 2cm lateral to the umbilicus.
Unlike an omphalocele, this herniation is NOT covered by a sac. Seen in neonatology. |
| intestinal obstruction |
a blockage of the bowel lumen prohibiting the passage of material. Common symptoms
include constipation and obstipation, abdominal swelling and abdominal pain. Treatment
includes intravenous fluids, rest, nasogastric suction and surgery in select cases when the
obstruction does not resolve with conservative management. |
| peritonitis |
inflammation of the peritoneum, a condition marked by exudations in the peritoneum of serum,
fibrin, cells and pus. It is attended by abdominal pain and tenderness, constipation, nausea and
vomiting, and moderate fever. |
| malrotation of gut |
abnormal or incomplete rotation of bowel that may be associated with a narrow attachment of
small bowel mesentery. This permits rotation, presenting as midgut volvulus, which is a
surgical emergency due to the twisting on the vascular pedicle. It is often an isolated finding,
but 20% are associated with: duodenal atresia, annular pancreas, duodenal
diaphragm. It typically is diagnosed in children under one month of age. |
| volvulus |
the twisting of the intestines which causes obstruction and colic. (Latin, volvo = to roll) |
| intussusception |
a telescoping of one portion of the intestine into another. This results
in reduced blood supply to the affected portion of the intestine. Intussusception is seen almost
exclusively in children between the ages of 5 months and 1 year. It is three times more
common in boys and the exact cause is unknown. In older children, tumors and polyps can
cause intussusception. The classic finding is "currant jelly stools", and is sometimes
accompanied with pain, emesis, lethargy, and a tubular mass which is palpable. |
| colectomy |
surgical resection of part or all of the large intestine. This may be performed as an "open" procedure or laparoscopically. It is routinely performed for conditions such as colon cancer, diverticular disease, inflammatory bowel disease, and intestinal blockage. A total colectomy refers to removal of the entire large intestine. Hemicolectomy refers to removal of only a portion of the large intestine. |
| rebound tenderness |
when pressure is applied to the abdominal wall and then suddenly removed, extreme localized pain is felt. |
| bezoars |
concretions formed in the alimentary canal of swallowed hair, fruit, or vegetable fibers. |
| hypovolemia |
a deficiency in the amount of circulating plasma in the body |
